The 358 prisoners who died when a Honduran prison burned down had been locked inside an overcrowded facility, where most inmates had never been charged or convicted, according to a government report.

More than half of the 856 inmates of the Comayagua farm prison were either awaiting trial or being held as suspected gang members, according to a report sent by the Honduran government this month to the United Nations, and seen by Associated Press.

A fire started by an inmate tore through the prison on Tuesday night, burning and suffocating men in their locked cells as rescuers searched for keys. It was the world's deadliest prison fire in a century.

Survivors told of climbing walls to break the sheet metal roofing and escape, only to see prisoners in other cell blocks being burned alive. Others burned to death on the roof.

According to the report, on any given day there were about 800 inmates in a facility built for 500. There were 51 guards by day and 12 at night when the fire happened.

The prison had no medical or mental healthcare and the budget allowed less than $1 (64p) per day per prisoner for food. Prisoners can be imprisoned under the strict Honduran anti-gang laws simply for having a tattoo, the report said. The UN condemns this as a violation of international law.

The Honduran national prison system director, Danilo Orellana, declined to comment on the supervision or the crowded conditions. The president, Porfirio Lobo, has suspended Orellana and other top prison officials.

The fire burned through six barracks, each holding between 70 and 105 inmates in four levels of bunk beds. Bodies were found piled up in the bathrooms, where inmates apparently fled to the showers, hoping the water would save them. Some were found in baths and laundry sinks.

The inmate who started the fire gave warning, phoning the state governor and screaming he was going to burn the place down. The man, who has not been named, lit a mattress a few minutes later. Fire crews said they rushed to the prison, arriving two minutes after a call for help because the fire station was nearby. But the handful of guards held them out for 30 minutes, saying they thought the screams were a prison break and a riot. Rescuers said that when they were finally allowed in they could not find keys or guards to unlock the barracks.

On Thursday morning, officials continued their investigation at the prison. "Conditions at Comayagua? I'd have to say among the worst in Honduras," said Ron Nikkel, the president of Prison Fellowship International, who visited the facility in 2005. "It was very congested, there's not enough food, it's dangerous and dirty."

The US state department has criticised the Honduran government for harsh prison conditions, citing severe overcrowding, malnutrition and lack of adequate sanitation. Human rights groups and the US government say inmates with mental illnesses, as well as those with tuberculosis and other infectious diseases, are routinely held among the general prison population.